The present invention relates to a machine for packaging filter paper pockets or bags containing substances powdered or in the form of small leaves for the preparation of infusions.
More specifically the present invention relates to a machine for the packaging of filter-paper pockets containing a tablet of fresh coffee powder, the pockets in question being joined together to form a strip or continuous ribbon which feeds intermittently an infusion unit of the usual type for the preparation of expresso coffee.
These machines for the preparation of expresso coffee are known and have acquired widespread use especially in the form of automatic distributors operated by coins or tokens. Machines are also known for packaging continuous strips of paper which have at regular intervals filter pockets containing freshly ground coffee.
These machines consist essentially of a traversing table, a lower ribbon of paper on which are formed at regular intervals recesses in which is deposited a predetermined amount of coffee powder which is deposited in the form of a tablet. On this lower ribbon there is superimposed an upper ribbon of paper which covers the individual tablets of fresh coffee powder, after which the two superimposed ribbons are welded, e.g. by thermosealing, along the entire periphery of each measure or tablet of fresh coffee powder.
An example of said machines for the packaging of strips of paper having at regular intervals filter pockets containing fresh ground coffee is described and claimed in the Italian application for utility model No. 23186-B/84 filed Sept. 18, 1984 by the same applicant as of the present application.
Said invention consists of a machine for the packaging of said pockets or bags of filter paper containing a measure of the substance from which the infusion is to be made, said machine comprising a conveyance table on which there advances in steps a plurality of jaw devices having a jaw moving between an open position and a closed position in relation to a fixed jaw, said table being arranged beneath a series of processing devices comprising first means of forming lower cavities in the lower paper ribbon fed upstream on said lower jaw, a metering device for the fresh coffee powder, a pressing member for the measure of coffee powder deposited on lower paper ribbon advancing intermittently, means of feeding and positioning the upper layer of paper of said pocket, and thermosealing means, said jaw devices comprising magnetically controlled means tending to hold said moving jaw closed against said fixed jaw while between said fixed jaw and said moving jaw is interposed said lower or supporting paper ribbon and with said moving jaw there is integral a drive pin engaged by cam means which drive the moving jaw between the open and closed position.
The machine described in the abovementioned application operates in a decidedly satisfactory manner but there remains a certain complexity of operation linked to said jaw devices operating between an open and a closed position and the need of having a very long chain of said jaw devices because of the various phases of the preforming of the lower ribbon, metering and pressing of the powder, feeding, positioning and forming of the upper ribbon, and thermosealing of the two ribbons performing in succession in distinct and contiguous stations or members of said machine.
An object of the present invention is to provide an improved machine for the packaging of filter pockets or bags of the abovementioned type and, in particular, a mechanism without jaws which would however permit holding firmly said first paper strip during the various pocket forming operations.
Another specific object of the present invention is to shorten as much as possible the chain formed of cups without jaws, using a tool which performs simultaneously with a single action the highest possible number of operations.
Another object of the present invention is to press the powder designed to fill said pockets in such a manner as to form a layer of the most uniform thickness possible.
Finally, another specific object of the present invention is to return all the coffee powder particles to within the layers forming the pockets in such as a manner as to eliminate all scattering of powder and hence the formation of defective pockets.